South Queensferry is near Edinburgh; if you get a chance you should definately get to the castle there.

I have driven through Greenock: it seems pleasant but I don't know much about it, though I have friends who are from around there; I've been to nearby Wemyss Bay (pronounced "weems bay") and Skelmorlie and enjoyed my time there.

Invergordon is in the beautiful Moray Firth; you can see an odd juxtaposition of seals basking on the dunes (and if you're lucky, dolphins), and oil platforms parked in the waters. There's a great view of the Black Isle and the firth from the Cromarty Road Bridge (more of a causeway, I think!):

picture of the Moray Firth looking towards Invergordon